Hydraulic device

ABSTRACT

A hydraulic motor-pump assembly including a housing, a chamber formed in the housing, a shaft journalled in the housing and extending into the chamber and a gear set in the chamber including an externally toothed rotor mounted fast on the shaft and an internally toothed stator assembly surrounding the shaft in meshing relation. The stator assembly is geared to the housing so as to cause, in response to relative rotation of the rotor, orbital movement of the stator assembly about the axis of the rotor and rotational movement of the stator assembly about its own axis at a speed less than the speed of rotation of the rotor. Certain passages, ports and the like are provided in the housing and in the stator assembly for directing high and low pressure fluid to and from the expanding and contracting fluid pockets formed between the teeth of the stator assembly in a manner providing high operating efficiency. The motor-pump assembly has wide application including use in a vehicular hydraulic motor drive arrangement.

United States Patent [191 Goff et a1.

[ HYDRAULIC DEVICE [75] Inventors: Raymon L. Goff; Frederick D. Vennble,both of Lafayette, Ind.

73 Assignee: T n w Inc., Cleveland, Ohio [22] Filed: Feb. 1, 1971 [21]Appl. No.: 111,190

Related 1.1.8. Application Data [62] Division of Ser. No. 841,405, July14, 1969, Pat. No.

[52] US. Cl ..l80/66 F [51] llnt. C1. ..B60k 7/00 [58] Field of Search..l80/66 F, 44 F, 44 M, 180/66; 418/61 [56] References Cited UNITEDSTATES PATENTS 3,302,741 2/1967 Brazuk 180/66 F X 3,391,608 7/1968 Huber..418/61 X 3,490,383 1/1970 Parrett ..418/61 X 2,989,951 6/1961 Charlson..418/61 X 2,418,123 4/1947 Joy ..l80/66 F 2,679,300 5/1954 Nubling..180/66 R 3,627,454 12/1971 Goff et al. ..418/61 Apr. 10, 1973 PrimaryExaminerBenjamin Hersh Assistant Examiner-Milton L. SmithAttorney-Carlton Hill et al.

[57] ABSTRACT A hydraulic motor-pump assembly including a housing, achamber formed in the housing, a shaft journalled in the housing andextending into the chamber and a gear set in the chamber including anexternally toothed rotor mounted fast on the shaft and an internallytoothed stator assembly surrounding the shaft in meshing relation. Thestator assembly is geared to the housing so as to cause, in response torelative rotation of the rotor, orbital movement of the stator assemblyabout the axis of the rotor and rotational movement of the statorassembly about its own axis at a speed less than the speed of rotationof the rotor. Certain passages, ports and the like are provided in thehousing and in the statorassembly for directing high and cationincluding use in a vehicular hydraulic motor drive arrangement,

5 Claims, 12 Drawing figures PATENTLD 1 @1973 3.726355 sum 6 BF 8 2 5 IN VENTORS Pay 401v A. 60 FF FREDERICK O. 1/6/V4646 PATEHTED 015175726,356

sum 7 OF 8 M INVENTORS RA 7M0 Z. GoFF FR 062?, 0.14%; By ATTORNEYSHYDRAULIC DEVICE CROSS REFERENCE TO RELATED APPLICATIONS Thisapplication is a division of application Ser. No. 841,405 filed July l4,l969, now US. Pat. No. 3,627,454.

BACKGROUND OF THE INVENTION This invention relates generally to thefield of hydraulic motor-purnp assemblies and more particuthe rotor inmeshing relation. The rotor generally has one less tooth than does thestator and the teeth of both gears are so configured that in response torelative rotation of the gears the axis of one will orbit about the axisof the other. This relative rotational and orbital movement of the gearscauses sequentially alternately expanding and contracting fluid pocketsto be formed between the teeth of the stator.

A rotatable work input-output shaft is connected to a rotatable one ofthe gerotor gears, and when the assembly is used as a motor, highpressure fluid is directed to the expanding fluid pockets and low pressure fluid is directed from the contracting fluid pockets, therebycausing rotation of the shaft. Corresponding'ly, when the assembly isused as a pump, the shaft itself is rotated, thereby drawing lowpressure fluid to the expanding fluid pockets and expelling higherpressure fluid from the contracting fluid pockets.

Fluid is directed into and out of the expanding and contracting pocketsby virtue of valve means which may include one or both of the gerotorgears. The valve means operates in timed relation to'the movement of thegears and for that reason may be referred to conveniently as commutationmeans.

Numerous arrangements of gerotor gear sets are known in the prior art.In some arrangements the stator is held stationary while the rotor bothrotates and orbits. In other arrangements the rotor remains stationarywhile the stator both rotates and orbits. In still other arrangementsone of the gears rotates while the other orbits.

In all of these arrangements the commutation means must be effective todirect the fluid into and out of the expanding and contracting fluidchambers in timed relation with the movement of the gears.

Gerotor gear sets and hydraulic pump-motor assemblies which incorporatesuch gear sets may be more suitable for certain applications than forothers. The motor-pump assembly of the present invention, for example,has particular utility in the field of vehicular drive mechanisms as aresult of its high torque and high operating efficiency capabilities.

SUMMARY OF THE INVENTION The present invention may be summarized ascomprising a hydraulic motor-pump assembly which includes a gerotor gearset constructed and arranged so that the axis of the rotor remainsaligned with the axis of the work input-output shaft while the statorassembly rotates relative to the rotor and the axis of the statorassembly orbits about the axis of the rotor. The commutation meansincludes the stator assembly in which certain pas sages, ports and thelike are formed to direct the fluid into and out of the expanding andcontracting fluid pockets in timed relation to the relative movement ofthe gerotor gears. The stator assembly is geared to the housing of themotor-pump assembly in a manner whereby the stator assembly rotatesrelative to the housing at a speed much less than the orbital speed ofthe stator assembly, as will be understood by those skilled in the art.

The commutation means provides what is referred to herein as phase-shiftcommutation. By the term phase-shift is meant that the control ofcommutation of high and low pressure fluid with the expanding andcontracting fluid pockets is accomplished by controlling the opening andclosing of fluid flow ports located respectively, relative to the axisof the rotor, in angularly offset relation to the fluid pockets into andout of which they control the flow of fluid.

An object of the present invention is to provide a highly efficient,high torque hydraulic motor-pump assembly that is relatively inexpensivein manufacture, has utility in a wide variety of applications and isparticularly suited in vehicular fluid motor drive arrangements.

In such vehicular drive applications the housing of the assembly may bemounted fast to the frame of the vehicle and the wheel mounted for jointrotation on the work output shaft. On the other hand, the shaft may beconnected fast to the vehicle frame and the wheel connected in fixedassembly to the housing of the assembly. The former application isparticularly suited for higher vehicular speed whereas the latterapplication is particularly suited for higher torque, lower speedapplications.

Several embodiments of a stator assembly constructed in accordance withthe principles of the present invention are illustrated herein. Each ofthese embodiments may have particular utility in certain applicationsand may advantageously utilize different modes of construction andfabrication.

Other objects, features and advantages of the present invention will bereadily apparent from the following description of certain preferredembodiments thereof, taken in conjunction with the accompanying drawing,although variations and modifications may be effected without departingfrom the spirit and scope of the novel concepts of the disclosure.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross-sectional view of ahydraulic motorpump assembly constructed in accordance with theprinciples of the present invention.

FIGS. 2, 3 and 4 are cross-sectional views taken along lines II--II,III-Ill and IV-IV in FIG. 1.

FIG. 5 is a cross-sectional view of another embodiment of a hydraulicmotor-pump assembly constructed in accordance with the principles ofthis invention.

FIG. 6 is similar to FIGS. 1 and 5 and illustrates yet anotherembodiment of a motor-pump assembly constructed in accordance with thepresent invention.

FIGS. 7-10 are cross-sectional views taken along lines VIIVII,VIII-VIII, IX-IX and X--X in FIG. 6.

FIG. 11 is a cross-sectional view of a vehicular motor-drive arrangementincluding a hydraulic motorpump assembly similar to that as shown inFIG. 1., the housing of the assembly being connected fast to the frameof the vehicle and the shaft of the assembly rotatably mounting a wheel.

FIG. 12 is a cross-sectional view of another vehicular motor-drivearrangement in which the wheel is mounted on the housing of themotor-pump assembly and the shaft is connected fast to the frame of thevehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1-5, ahydraulic motor-pump assembly constructed in accordance with theprinciples of the present invention is indicated generally at referencenumeral 10. The assembly comprises a housing 11 having a body portion12, an annular spacer member 13 and an end cap 14. An end wall 16 of thebody 12 faces a spaced parallel end wall 17 of the end cap 14 which,together with a cylindrical wall 18 of the spacer member 13, forms acylindrical chamber 19 within the housing 11.

A work input-output shaft 20 is journalled in the housing 11 by means ofbearing assemblies 21 and 22 and is axially aligned with the chamber 19.When the assembly 10 is being utilized as a pump the shaft 20 may beconnected to suitable drive apparatus and serves as a work input shaft.On the other hand when the assembly 20 is being utilized as a motor theshaft 20 may be coupled to suitable driven apparatus and serves as awork output shaft. An outer end 23 of the shaft 20 may be splined as at24 or otherwise adapted for suitable connection to the driving or drivenapparatus. A suitable seal assembly as indicated at reference numeral 26is provided near the outboard end of the shaft 20 to prevent loss offluid from the housing 11 past the shaft 20.

Disposed within the chamber 19 is a gear set indicated generally atreference numeral 27 which, when the assembly 10 is being utilized as ahydraulic pump, is operated by the shaft 20 to increase fluid pressurethereacross. Conversely, when the assembly 10 is being utilized as ahydraulic motor drive pressurized fluid acts on the gear set 27 torotate the work output shaft 20.

The gear set 27 comprises a pair of gear members 28 and 29. The gearmember 28 is mounted fast to the shaft 20 for joint rotation therewithby means of a spline connection including a splined portion 30 of theshaft 20 and a splined bore 31 of the gear member 28.

Formed on an outer wall 32 of the gear 28 are a series of gear teeth 33which, in the embodiment of the invention illustrated in FIGS. l-5, aresix in number. Since the gear member 28 rotates on a fixed axis it isconveniently referred to herein as a rotor.

The gear member 29 surrounds the rotor 28 in the chamber 19 andcomprises an inner cylindrical wall 34 and an outer cylindrical wall 36.A series of cylindrically shaped recesses 37 are formed in the innerwall 34 and disposed within each is a tubular member 38. Since the wallsof the recesses 37 envelop the periphery of the tubular members 38through an are greater than 180 the members 38 are'securely maintainedwithin their respective recesses 37.

The tubular members 38 serve as gear teeth for the gear member 29 andare greater in number by one than the teeth 33 of the rotor 28. Becauseof this difference in number between the teeth 33 of the rotor 28 andthe mating teeth 38 of the gear member 29 rotation of the rotor 29 aboutits fixed axes has the effect of causing the gear member 29 to move inan orbital fashion about the rotor 28 or both orbit and rotate about theaxis of the rotor 28. As a result of this orbital path of travel theouter gear member 29 is conveniently referred to herein as a statorassembly. Gear sets employing an externally toothed gear member and aninternally toothed gear member surrounding the externally toothedmember, in which the number of internal teeth exceeds by one the numberof external teeth, are often referred to by those skilled in the art asgerotor gear sets, one of the peculiar characteristics of which involvesthe relative movement thereof whereby, aupon rotation of either one, thegear members both orbit and rotate relative to one another. The ratio ofrelative orbital speed to rotational speed of the gear members is equalto n+l where n equals the number of external teeth of the inner gearmember.

In the embodiment illustrated in FIGS. 15 the stator assembly 29 of thegerotor gear set 27 comprises a series of gear teeth 39 found on theouter peripheral wall 36 thereof. A cooperating series of teeth 40 isformed on the cylindrical wall 18 of the spacer portion 13. The numberof teeth 40 exceeds the number of teeth 39 to the end that, as thestator assembly 29 orbits about the rotor 28, that is, as the axis ofthe stator assembly 29 moves about the axis of the rotor 28 in acircular path of travel, the stator assembly 29 will also rotaterelative to the housing '11.

In the embodiment-illustrated the gear teeth 39 equal 52 in numberwhereas the gear teeth 40 equal 54 in number. Thus for each completemovement of the stator assembly 29 through an orbital path of travel thestator assembly 29 will rotate in the housing 11 2/54 or l/27 of arevolution about its own axis.

As the gear members 28 and 29 rotate and orbit relative to one anotherthe gear teeth 33 and 38 form sequentially alternately expanding andcontracting fluid pockets between the teeth 38 of the stator assembly29. These fluid pockets are indicated respectively in FIG. 3 atreference characters 41,,-41,,.

To illustrate this principle, assume the rotor 28 is rotated in acounterclockwise direction as indicated by the arrow 42 in FIG. 3. Thefluid pocket 41,, will thereby be contracted or reduced in volume fromthat which would be indicated in FIG. 3. Similarly fluid pockets 41,,and 41,. would tend to become reduced in volume.

On the other hand fluid pockets 41,,, 41 and 41, would tend to increasein volume. Fluid pocket 41,, would tend to vary little in volume untilthe rotor 28 had turned through a substantial number of degrees sincethe gear tooth 33 disposed therewithin initially varies its positioninitially at a slower rate than the remaining gear teeth 33.

Meanwhile such counterclockwise rotation of the rotor 28 causes thestator assembly 29 to tend to orbit in a clockwise direction at anorbital speed six times greater than the rotational speed of the stator28. However, as the stator assembly 29 orbits in a clockwise directionthe gear teeth 39 and 40 cause rotation of the stator assembly 29 in acounterclockwise direction.

' Thus in the disposition of the parts shown in FIG. 3, for eachcomplete revolution of the rotor 28 about its axis the stator assembly29 will orbit six times, and for each movement of the stator assembly 29through one complete orbital path of travel it will rotate 1/27 of arevolution about its axis relative to the housing 11. The fluid whichacts upon or is acted upon by the hydraulic motor-pump assembly entersand leaves the housing 11 through a pair of openings indicated atreference numerals 43 and 44, both of which may be threaded toconveniently receive suitable fluid conduits. When the assembly 10 isbeing utilized as a motor the direction of rotation of the work outputshaft will be determined by which of the openings 43 and 44 is connectedto the high pressure side of the main fluid power pump and which isconnected to the low pressure side of the main pump. The direction ofrotation of the shaft 20 may be reversed simply by reversing theconnections of the openings 43 and 44 to the main power pump.

On the other hand when the assembly 10 is being utilized as a hydraulicpump the direction of rotation of the work input shaft 20 determineswhich of the openings 43 and 44 will receive the low pressure fluid andwhich will discharge the higher pressure fluid to the intended point ofuse. v

' When the assembly 10 is being utilized as a hydraulic motor it isnecessary that the high pressure fluid be directed to the expandingfluid pockets 4l,,-41,, whereas when the assembly 10 is being utilizedas a pump the contracting fluid pockets communicate with that one of theopenings 43 and 44 delivering the high pressure fluid from the assembly10. The fluid acting upon or being acted upon by the motor-pump assembly10 is directed to and from the expanding and contracting fluid pockets41 -41,, in timed relation to the rotational and orbital movement of thegear members 28 and 29 by means including the stator assembly 29 andreferred to generally as commutation means. The fluid such as oil or thelike is conducted by means of fluid passages 43,, and 44,, from theopenings 43 and 44 to a pair of annularly shaped grooves 43,, and 44,,formed in the radial wall 16 of the chamber 19. The grooves 43,, and44,, are separated from each other by a ridge or land 46 as shown inFIGS. 1 and 2.

The stator assembly 29 comprises a stator member 29,,, the axialdimension of which corresponds to the axial dimension of the rotor 28and of the tubular members 38, and a spacer plate 29,. The spacer plate29,, is firmly secured to the stator 29,, by means of a plurality ofsuitable fasteners such as rivets indicated at reference numeral 47. Oneradial wall 48 of the spacer plate 29,, engages in sliding relation withthe radial wall 16 of the housing body member 12 whereas an oppositewall 49 abuts an adjacent side wall 50 of the stator member 29,, andengages in sliding relation a corresponding side wall 51 of the rotor28.

Since the spacer plate 29,, moves jointly with the stator member 29,, itis apertured as 52 to accommodate orbital movement around the shaft 20.The diameter of an outer peripheral wall 53 of the spacer plate 29,, is

spacer plate 29,. Communicating with the apertures curved fluid flowpassageways 56,,-56,, which are formed in the face of the end wall 50 ofthe stator member 29,, and open respectively to their correspondingfluid pockets 41,,-4l,, through ports 57,,-57,,.

The triangularly shaped apertures 54,-54, are angularly offset fromtheir respective ports 57,,57,, (and thus the fluid pockets 41,41, withwhich they respectively communicate) by about 90 with respect to theaxis of the stator assembly 29. This angularly offset relation serves toprovide the commutation system referred to herein as phase-shiftcommutation.

To further explain, reference is made to the relative disposition ofparts shown in FIGS. 3 and 4 wherein the axis of the stator assembly 29is vertically aligned with respect to the axis of the rotor 28. Assumingthat the motor-assembly 10 is being utilized as a hydraulic motor andthat the shaft 20 is to be rotated in the direction indicated by thearrow 42, the pressurized fluid from the discharge side of the mainpower pump to which the assembly 10 is connected will be coupled to thefluid opening 43 and the return side of the main power pump coupled tothe fluid opening 44. The groove 43,, is therefore subjected to highpressure fluid and the groove 44,, subjected to low pressure fluid.

In the position of the parts shown in FIGS. 3 and 4 the stator assembly29'must orbit counterclockwise to rotate the shaft 20 counterclockwise,and to accomplish this result it is preferable for the commutationsystem to provide for communication of all of the fluid pockets on theright-hand side of the axis of the stator assembly 29 (all of theexpanding fluid pockets 41,,-41,, with high pressure fluid to applymaximum motive forces to the stator assembly 29, and as a resultthereof, to the rotor 28.

Phrased differently, maximum force is applied to the stator assembly 10when all of the fluid pockets 4l,,-4l located on one side of a lineextending through the axis of the rotor 28 and the point at which thestator assembly 29 contacts the cylindrical wall 18 of the chamber 19communicates with high pressure fluid and all of the remaining fluidpockets 4l,,41,, communicate with low pressure fluid.

In FIG. 3 the grooves 43,, and 44,, and the land 46 have been indicatedin phantom lines to indicate the substantially the same as the diameterof the outer wall relative positions thereof when the stator assembly 29is in the uppermost position thereof as shown in FIGS. 3 and 4. Sincethe relative orbital movement and rela-' tive positions of the statorassembly 29 and the stationary grooves 43,, and 44,, determine which ofthe grooves 43,, and 44 communicates with each of the fluid pockets4l,,4l,,, the angular offset relation between the fluid pockets 41,41,(and accordingly the ports 57,,57,,) and the triangularly shapedapertures 54,,54 in the spacer plate 29,, (referred to herein asphase-shift commutation) assures maximum input, output and efficiency ofthe motor-pump assembly 10.

The embodiment illustrated in FIG. 5 is similar to that shown in FIGS.l-4, the principal differences being that the low and high pressurefluid are supplied to and discharged from both of the axially spacedends of the fluid pockets, rather than from only the right end of thepockets as obtains in the FIGS. 1-4 embodiment. Since many of theindividual parts of the embodiment shown in FIG. are similar oridentical to corresponding parts shown in FIGS. 14 the same referencenumerals will be used for corresponding parts only increased by thenumber 100.

Thus in FIG. 5 the motor-pump assembly 100 comprises a pair of fluidopenings 143 and another pair of fluid openings 144. Each of the fluidopenings 143 communicates through a corresponding passage 143,, to anannular groove 143,,, one of which is formed in the radial wall 116 ofthe body member 112 and the other of which is formed in the radial wall117 of the housing end cap 114.

The stator assembly 129 includes a single stator member 129,, but a pairof spacer plates 129,, are located respectively on opposite sides of thestator member 129,,. A series of triangularly shaped apertures154,,154,, are formed in each of the spacer plates 129,, and a series ofelongated fluid flow passages 156,,156,, are formed in each of the endwalls 150 and 150' of the stator member 129,,.

The provision of the dualfluid openings 143 and 144, the two sets ofgrooves 143, and 144,, as well as the duplication of the other portionsof the commutation means serve to reduce pressure losses through theassembly 10, increase overall efficiency and performance characteristicsand reduce wear and prolong the useful life of the assembly by axiallybalancing the fluid pressure generated forces acting on the gerotor gearset 127.

Another embodiment of a hydraulic motor-pump assembly constructed inaccordance with the principles of the present invention is illustratedin FIGS. 6-10 wherein reference numerals indicating parts similar tothose included in the former two embodiments are indicated by similarreference numerals in the 200 series.

In the embodiment shown in FIGS. 6-10 the stator assembly 229 comprisesa stator member 229,, and a pair of spacer members 229,, disposed onaxially opposite sides of the stator member 229,, Sandwiched in betweenthe stator member 229,, and the pair of spacer plates 229,, are a pairof stator plates 229,. The stator plates 229, are securely fastened tothe stator member 229,, by a plurality of fasteners as indicated on thereference numeral 58.

In this embodiment the apertures in the spacer plate 229,, whichregister alternately with the high and low pressure grooves 243,, and244 are flatter and more circumferentially elongated than the triangularapertures 54,,54 of the FIGS. 1-4 embodiment. Furthermore the elongatedfluid flow passageways 256,, and 256,, are formed in the faces of flatradial walls 59, 59 of the stator plates 229,, 229,, rather than in theface or faces of the stator member 229,.

Furthermore the ports 257,,257,, which communicate with the expandingand contracting fluid pockets 241,,-241,, are formed in radial walls 60,60 of the stator plates 229,, 229,, rather than in the inner wall 34 ofthe stator member 29,,, as is found in the FIGS. 1-4 embodiment.

The fluid openings 243 and 244 are found in the end cap 214 rather thanin the body portion 212 and communicate 9 with the annular grooves 243,,and 244,, formed in the radial wall 217 of the end cap 214.

Another pair of grooves 243,, and 244,, are formed in the face 216 ofthe body portion 212. The two outer grooves 243,, communicate with oneanother between the outer peripheral wall of the stator assembly 229 andthe cylindrical wall 218 of the chamber 219.

The pair of reduced diameter grooves 244,, communicate with one anotherthrough a series of radially extending passageways 61 also formed in theradial walls 216 and 217 of the body portion 212 and the end cap 214 andradial passages 62 and an interconnecting axial passage 63 formed in theinput-output shaft 220.

Thus the embodiment shown in FIGS. 6-10 includes commutation means fordirecting the high and low pressure fluid to and from the expanding andcontracting fluid pockets 24l,,241,, from axially opposite sides of therotor 228 and the stator member 229,, even though there is only a singlepair of fluid openings 243 and 24-4. In addition, the fluid is directedinto and out of the fluid pockets 241,,241,, axially through the axiallyfacing ports 257,,257,,, rather than the radially facing ports 57,,-57,,of the FIGS. 14 embodiment.

FIG. 11 discloses an embodiment of the hydraulic motor-pump assemblyshown in FIGS. 1-4 adapted for utilization in a vehicular drive system.A portion of the frame of the vehicle on which the assembly 10 ismounted is indicated at reference numeral 66, and the end cap 14 issecured fast to the frame 66 by means ofa plurality of suitablefasteners such as the nuts and bolts indicated at 67 and 68respectively.

The shaft 20, which in this application serves as a work-output shaft,is slightly axially tapered as indicated at 69 and keyed as at 70 toreceive the hub 71 of a wheel 72 of the vehicle. The fluid openings 43and 44 are connected to the high and low pressure sides ofa main powerfluid pump, preferably through a valving mechanism enabling thedirection of rotation of the shaft 20 to be reversed without reversingthe operating direction of the main power pump. Accordingly, when theassembly 10 is connected to the main pump the wheel 70 will be rotatedrelative to the frame 66 by virtue of the relative orbital androtational movement of the gears of the gerotor gear set 27 and as aresult of the rotation of the shaft 20.

FIG. 12 is expositive of another embodiment of a hydraulic motor-pumpassembly constructed in accordance with the principles of the presentinvention and utilized in a vehicular drive system. Since many of thecomponents of the motor-pump assembly correspond closely or identicallyto those found in FIGS. 14 such corresponding parts or components willbe given similar reference numerals although increased to the 300series.

In this embodiment the housing 311 of the motorpump assembly 310 issecurely connected to the rim 371 of the vehicular wheel 372 by virtueof a plurality of fasteners indicated at reference numerals 73. On theother hand the shaft 320, through an extension 74 thereof, is securelyfastened to the vehicular frame 366, whereby the shaft 320 is maintainedin a fixed or stationary relation with respect to the frame 366.

Thus in the FIG. 12 embodiment of the invention the housing 311 rotateson a fixed axis rather than the shaft 320, which remains stationary. Thefluid openings 343 and 344, rather than being formed in the rotatinghousing 311, are formed in the extension 74 of the fixed shaft 320, andcommunicate by virtue of fluid passages 76 and 77 formed in the shaft320 and corresponding passages 78 and 79 formed in the body portion 312to the annular grooves 343,, and 344,, formed in the radial wall 16 ofthe body portion 312.

It will be appreciated by those skilled in the art that all of thevarious embodiments of the motor-pump as sembly disclosed herein aresuitable for use in the vehicular drive arrangement as disclosed inFIGS. 11 and 12. In addition, of course, all of the illustratedembodiments may be advantageously utilized in a wide variety of fieldsof use.

What we claim is:

l. A hydraulic motor drive mechanism for vehicles comprising a housingadapted to be mounted fast on the frame of the vehicle and having meansforming a gear chamber therein and a shaft journalled thereon extendinginto said chamber,

a wheel mounted on said shaft for joint rotation,

a gear set in said chamber including an externally I toothed rotormounted fast on said shaft for joint rotation and an internally toothedstator assemblysurrounding said rotor and orbitally and rotationallymovable relative thereto for providing alternately expanding andcontracting fluid pockets between the teeth of said stator-assembly,fluid-conducting means for communicating high and low pressure fluid tosaid chamber, means formed on said stator assembly and on said housingfor restraining said stator assembly against rotation at the rotationalspeed of said rotor and for guiding said stator assembly in said orbitalmovement, and i phase-shift commutation means including said statorassembly disposed in said chamber for directing fluid between said fluidconducting means and said expanding and contracting fluid pockets inresponse to orbital and rotational movement of said stator assemblyrelative to said rotor and in timed relation therewith,

said chamber-forming means comprising a stationary radial wall, saidstator assembly comprising a radial wall in sliding engagement with saidchamber radial wall, and said phase-shift commutation means comprising apair of radially spaced concentric annular grooves formed in-the face ofthe stationary radial wall of said chamber in axial alignment with saidshaft and a series of ports formed in the radial wall of said statorassembly and arranged in circular pattern to register sequentially andalternately with said grooves in response to orbital movement of saidstator assembly.

2. The invention as defined in claim 1 wherein said fluid conductingmeans comprises a fluid inlet opening and a fluid outlet opening formedin said housing.

3. A vehicular hydraulic motor drive mechanism comprising a pair ofrelatively movable members including a housing and a shaft journalledfor rotation on a fixed axis on said housing,

said housing having means including a stationary radial wall forming agear chamber,

said shaft extending into said chamber,

a fluid inlet opening and a fluid outlet opening formed in said motordrive mechanism, a gear set in said gear chamber including an externallytoothed rotor mounted on said shaft for joint rotation therewith on saidfixed axis and an internally toothed stator assembly surrounding saidrotor and movable orbitally and rotationally relative thereto to providea series of sequentially alternately expanding and contracting fluidpockets between the internal teeth of said stator assembly,

means interconnecting said stator assembly and said housing forrestraining said stator assembly against rotation at the rotationalspeed of said rotor and for guiding said stator assembly in said orbitalmovement, means including first and second radially spaced concentricannular grooves formed in the face of said stationary radial wall andcommunicating respectively with said fluid inlet opening and said fluidoutlet opening,

fluid communication means including said stator assembly forcommunicating said expanding fluid pockets with one of said grooves andsaid contracting fluid pockets with the other of said grooves duringrelative orbital and rotational movement of said rotor and said statorassembly, and a wheel mounted fast on one of said relatively movablemembers,

the other of said relatively movable members being adapted forconnection in fixed assembly to the frame of the vehicle.

4. The invention as defined in claim 3 wherein said housing is connectedin fixed assembly to said frame and wherein said fluid inlet opening andsaid fluid outlet opening are formed in said housing.

5. The invention as defined in claim 3 wherein said shaft is connectedin fixed assembly to the frame of said vehicle and said fluid inletopening and said fluid outlet opening are formed in said shaft.

1. A hydraulic motor drive mechanism for vehicles comprising a housingadapted to be mounted fast on the frame of the vehicle and having meansforming a gear chamber therein and a shaft journalled thereon extendinginto said chamber, a wheel mounted on said shaft for joint rotation, agear set in said chamber including an externally toothed rotor mountedfast on said shaft for joint rotation and an internally toothed statorassembly surrounding said rotor and orbitally and rotationally movablerelative thereto for providing alternately expanding and contractingfluid pockets between the teeth of said stator assembly,fluid-conducting means for communicating high and low pressure fluid tosaid chamber, means formed on said stator assembly and on said housingfor restraining said stator assembly against rotation at the rotationalspeed of said rotor and for guiding said stator assembly in said orbitalmovement, and phase-shift commutation means including said statorassembly disposed in said chamber for directing fluid between said fluidconducting means and said expanding and contracting fluid pockets inresponse to orbital and rotational movement of said stator assemblyrelative to said rotor and in timed relation therewith, saidchamber-forming means comprising a stationary radial wall, said statorassembly comprising a radial wall in sliding engagement with saidchamber radial wall, and said phase-shift commutation means comprising apair of radially spaced concentric annular grooves formed in the face ofthe stationary radial wall of said chamber in axial alignment with saidshaft and a series of ports formed in the radial wall of said statorassembly and arranged in circular pattern to register sequentially andalternately with said grooves in response to orbital movement of saidstator assembly.
 2. The invention as defined in claim 1 wherein saidfluid conducting means comprises a fluid inlet opening and a fluidoutlet opening formed in said housing.
 3. A vehicular hydraulic motordrive mechanism comprising a pair of relatively movable membersincluding a housing and a shaft journalled for rotation on a fixed axison said housing, said housing having means including a stationary radialwall forming a gear chamber, sAid shaft extending into said chamber, afluid inlet opening and a fluid outlet opening formed in said motordrive mechanism, a gear set in said gear chamber including an externallytoothed rotor mounted on said shaft for joint rotation therewith on saidfixed axis and an internally toothed stator assembly surrounding saidrotor and movable orbitally and rotationally relative thereto to providea series of sequentially alternately expanding and contracting fluidpockets between the internal teeth of said stator assembly, meansinterconnecting said stator assembly and said housing for restrainingsaid stator assembly against rotation at the rotational speed of saidrotor and for guiding said stator assembly in said orbital movement,means including first and second radially spaced concentric annulargrooves formed in the face of said stationary radial wall andcommunicating respectively with said fluid inlet opening and said fluidoutlet opening, fluid communication means including said stator assemblyfor communicating said expanding fluid pockets with one of said groovesand said contracting fluid pockets with the other of said grooves duringrelative orbital and rotational movement of said rotor and said statorassembly, and a wheel mounted fast on one of said relatively movablemembers, the other of said relatively movable members being adapted forconnection in fixed assembly to the frame of the vehicle.
 4. Theinvention as defined in claim 3 wherein said housing is connected infixed assembly to said frame and wherein said fluid inlet opening andsaid fluid outlet opening are formed in said housing.
 5. The inventionas defined in claim 3 wherein said shaft is connected in fixed assemblyto the frame of said vehicle and said fluid inlet opening and said fluidoutlet opening are formed in said shaft.